Njord Seminar with Marie Violay (École Polytechnique Fédérale de Lausanne)

Marie Violay (École Polytechnique Fédérale de Lausanne): Mechanical behavior of fluid-induced earthquakes

A poster for a Njord seminar showing presenter, title, date, Njord seal, and Zoom link.


Fluids play an important role in fault zone and in earthquakes generation. Fluid pressure reduces the normal effective stress, lowering the frictional strength of the fault, potentially triggering earthquake ruptures. Fluid injection induced earthquakes (FIE) are direct evidence of the effect of fluid pressure on the fault strength. In addition, natural earthquake sequences are often associated with high fluid pressures at seismogenic depths. Although simple in theory, the mechanisms that govern the nucleation, propagation and recurrence of FIEs are poorly constrained, and our ability to assess the seismic hazard that is associated with natural and induced events remains limited. Here we study the role of pore fluid pressure on fault mechanical behavior during the entire seismic cycle. i.e., strain rates from ~10-9/s (fault creep) to ~103/s (co-seismic slip). We reproduced at the scale of the laboratory miniature injection experiments. The velocity of the rupture propagation front, fault slip, dynamic stress drop and acoustic emission were recorded with a state of-the-art monitoring system. We demonstrated that the nature of seismicity is mostly governed by the initial stress level (i.e pore fluid pressure) along the faults and that the dynamic fault weakening depends on both fluid rheology and thermodynamic.


Published Jan. 29, 2021 3:28 PM - Last modified Apr. 12, 2021 5:44 PM